Impacting machine using dynamic reaction force



Feb. 24, 1970 w. H. GOETTL. ETAL 3,497,0

IMPACTING MACHINE USING DYNAMICfREACTION FORCE Filed Feb. 23, 1968 3 Sheets-Sheet 1 Feb. 24, 1970 w. H. GOETTL ETAL 3,497,017

' IMPACTING MACHINE USING DYNAMIC REACTION FORCE Filed Feb. 23, 1968 3 Sheets-Shem a 546K NOE V4 4 VE-S' INVENTOR5 I mLL/AM H. 6057;; Joy/v /Y/. 505772. 205527 6*. iV/zso/v 541.52g L. HEA/OEESQN 4 TTOEA/M United States Patent O US. Cl. 173-18 6 Claims ABSTRACT OF THE DISCLOSURE An impacting machine for soil compaction, post driving and the like, with an impactor empolying a weighted plunger freely reciprocating within a casing carrying an impacting head. The plunger is supported by the casing and is positively reciprocated to transfer dynamic forces to the casing and impacting head by reaction and without hammer impact. Down-pressure is supplied to the impactor either directly from a hydraulic operator which follows the downward movement of the casing to main tain a substantially constant pressure thereon or through a spring or compressed air chamber connection to a boom which supplies an initial down pressure and is then locked in position. A control circuit for the latter connection shows automatic operation until maximum compaction is obtained. The casing and impacting head reciprocate with a throw or excursion determined by the relative masses of the reciprocating plunger and the easing parts, the amount of down-pressure on the impactor, and the degree of compaction of the soil. When maximum compaction is reached, the casing, in effect, stands still to indicate this condition. The impactor is mounted on a ground vehicle or other ground support by a linkage providing for vertical movement thereof by a resilient connection to a standard backhoe boom on such a ground vehicle.

BACKGROUND OF THE INVENTION (1) This invention lies in the field of movable impacting machines for compacting soil, driving posts and like uses, particularly when mounted on ground vehicles.

(2) Ground vehicle impacting machines are known in the prior art, with both reciprocal hammer-anvil operation and movement of the impacting-head by reaction forces. However, the hammer-anvil type machines'have resulted in machine-part-pounding disproportionate to the impact forces exerted by the machine and limiting both the efficiency of the machine and its output capability. On the other hand, what reaction force impactors exist have been realtively ineffectual, with low output capabilities and low, clumsy or ineffectual downpressure application. An example of a dynamic force compactor is shown in Bo-dine, Jr., 2,897,734 whose structure, however, attempts to secure compaction by a plurality of generators and sonic beam generation.

SUMMARY OF THE INVENTION An object of this invention is the provision of an improved impacting machine employing a impactor utilizing dynamic reaction forces applied to an impacting head from a freely-reciprocating weightedp lunger without hammer impacts. Initial down-pressure is applied to the impacting head either directly by a hydraulic opeartor applying a substantially constant pressure to follow downward movement of the impacting head or from compressed springs or air connecting the impacting head to a mounting boom which supplies an initial down-pressure to compress the springs or air and is then locked in fixed position.

The impacting head is preferably directly mounted to a casing which is, in turn, movably connected to a ground support or vehicle to be raised and lowered relative thereto. The reciprocating plunger is mounted on and within the casing to reciprocate freely therein and transfer reaction forces to the casing through its mounting thereon, without hammer impact. The amount of reciprocation of the casing and impacting head is used to indicate the degree of compaction of soil upon which the impact head is operating, the casing, in effect, standing still when the impactor has reached its maximum output capability. A determination of maximum compaction can also be secured from a pressure gauge in the embodiment where constant hydraulic down-pressure is applied to the casing.

A further feature of the invention lies in an electrical control by which the impactor is automatically started and stopped and, when the casing fails to move downwardly for a predetermined time interval, the operation is terminated and an indicator operated to show that the impactor has reached its maximum capability.

The reciprocations of the casing and plunger will be somewhat isolated from the ground support or vehicle upon which the impactor is mounted by the hydraulic operator which supplies direct down-pressure or by the springs, air or other resilient material connecting the impactor to a boom which supplies initial down pressure by compressing the resilient material and is then locked. The impactor casing moves away from the boom as it and the impact head move independently downwardly as the soil is compacted or a post is driven.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a view, partly in side elevation and partly in vertical section, of an impacting machine according to the present invention;

FIGURE la is a horizontal sectional view on the line 1a1a of FIGURE 1;

FIGURE 2 is a diagrammatic representation of a hydraulic control system for the impactor of FIGURE 1;

FIGURE 3 is a vertical sectional view through another embodiment of this invention with the impactor mounted on a typical tractor backhoe boom through a spring connection, and showing two separate compaction indicating means;

FIGURE 4 is a view, partly in elevation and partly in sec ion, of another backhoe boom mounting, including limit switches operated at opposite extremes of the resilient connection;

FIGURE 5 is a diagrammatic representation of an electrical-hydraulic control system for the embodiment shown in FIGURE 4;

FIGURE 6 is a view, partly in elevation and partly in section, of another backhoe-boom-mounted impactor according to the present invention employing an air pressure chamber connection between the boom and the impactor; and

FIGURE 7 is a reduced, side-elevational view of the embodiment of FIGURE 1 mounted on a self-propelled ground vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to the embodiment of the invention illustrated in FIGURES 1 and 1a, the impacting machine utilizes an impactor 11 whose body portion comprises an elongated cylindrical casing 12 having end plates 13 and 14 integrally secured thereto, as by welding. At the front of the casing 12 are a pair of horizontally-spaced, integral flange plates 15 on which are pivotally mounted one of the ends of two pairs of parallel links 16 and 17, as by pins 18 and 19, respectively. The opposite ends of the links 16 and 17 are pivotally connnecting to horizontally-spaced flange plates 21, as by pins 22 and 23, respectively. A hydraulic operating cylinder 24 is pivotally mounted by pin 25, above the pin 22, on flange plates 21. Within the cylinder 24 is an operating piston 26 (FIGURE 2) from which a connecting rod 27 extends through the end cap of cylinder 24 opposite the pivot 25, the end of connecting rod 27 being pivotally connected to the pin 18. The flange plates 21 are rigidly secured, as by welding, to a portion 28 of any ground support, for example, a self-propelled tractor 30, as shown in FIGURE 7.

Mounted for free reciprocating movement within the casing 12 is a weighted plunger or piston 31 carried by a wrist pin 32 in a bearing 33 on the lower end of a connecting rod 34. The upper end of the connecting rod 34 carries a cylindrical bearing 35 within which is re ceived an eccentric or crank pin 36 on a crank shaft 37. The crank shaft 37 is mounted in bearings 38 and 39 carried in sleeve housings 41 and 42, respectively, integral with and located diametrically opposite each other in the walls of the casing 12. The housing 42 has an integral end cap 43 and to the housing 41 is mounted a hydraulic motor 44 by any suitable means, not shown. The motor 44 is connected to rotate the crank shaft 37 when supplied with hydraulic fluid under pressure through the line 45, the motor exhausting to a reservoir tank through the line 46.

The wrist pin 32 is disposed in a horizontal bore 47 through the plunger 31 which communicates with a transversely elongated vertical hole 48 through which the connecting rod 34 extends. The bottom of the plunger 31 is provided with an end bore 49 into which projects a guide pin 51 carried by the end plate 14 so as to maintain the plunger 31 out of contact with walls of the casing 12, the plunger being spaced from the inner casing wall by an appreciable distance at 52 to allow free passage of air past the plunger as it reciprocates.

From the bottom face of the end plate 14 projects an impacting post 53 which is thereby rigidly secured to casing 12 to reciprocate therewith. A compacting head, driving means or the like is mounted on the bottom of post 53, a compacting head 54 being shown in FIGURE 1 in association with soil to be compacted at 55. The direction of tractor travel is indicated by the arrow 56 so that the compacting head 54 is approaching an upgrade 57 in the soil to be compacted, as will be explained in the operation of this embodiment.

FIGURE 2 is a diagrammatic representation of the hydraulic system for controlling the impactor of the embodiment of FIGURE 1. The hydraulic fluid is contained in a reservoir tank 61 whence it is fed to a pump 62. A four-way manual control valve is shown at 63 in its neutral position where the hydraulic fluid from pump 62 feeds back into the tank 61 through ports 64 and 65. The valve 63 has additional ports 66 and 67, the port 66 being connected to a normally open two-way solenoid valve 68, a flow regulator 69 and the motor 44. A check valve 71, checking in the direction of the arrow, is in series with the motor 44, while a check valve 72 parallels the valve 68. The outlet of the flow regulator 69 is connected by a line 73 to the lowering port 74 of hydraulic cylinder 24. The line 73 is also connected to an adjustable pressure-release valve 75 which exhausts to the tank 61. The port 67 is connected to the motor exhaust line 46 and to the impactor-raising port 76 of the cylinder 24. The valve 68 has an electrical solenoid operator at 77.

The operation of the impactor embodiment of FIG- URES 1, 1a, 2 and 7 will now be described. As shown in FIGURE 2, the control is in a neutral position with the valve 68 in its normal open position and with the pump 62 feeding back into the tank 61. To effect a compacting operation, the manual valve 63 is moved downwardly to interconnect ports 64, 66 and ports 65 and 67, respectively. Connection of ports 65 and 67 connect the port 76 of cylinder 24 and the exhaust line 46 of motor 44 to the tank 61. The connection of ports 64 and 66 immediately sends hydraulic fluid under pressure through the normally open valve 68 to the port 74 whereupon the piston 26 in cylinder 24 moves outwardly to lower the impactor casing 12 and place a down-pressure thereon and on the compacting head 54 limited to the set pressure of relief valve 75. After the impactor has b en thus lowered, the solenoid 77 is energized to operate the valve 68 to cut otf position after which the port 74 is connected to the pump 62 only through the flow regulator 69 which maintains pressure to the cylinder 24 while insuring passage of the major output of the pump 62 through the motor 44. The down-pressure exerted by the piston 26 on casing 12 and compacting head 54 will be determined by the setting of the adjustable pressure relief valve 75 which maintains the pressure on line 73 constant at, for example, 250-750 p.s.i., depending on the setting thereof. The flow regulator 69 may be likewise adjustable between 0-7 gallons per minute, a practical example being: where pump 62 supplies 16 g.p.m., the flow regulator may be set to pass 1 g.p.m. while 15 g.p.m. flow through the motor 44.

As illustrated in FIGURES l and 7, the compacting head 54 travels continuously in the direction of the arrow 56, propelled by the tractor 30. The speed of travel will be set to secure maximum compaction of the soil 55 and this is determined by the rate and degree of reciprocation of the casing 12 and head 54. Thus, while the soil 55 is relatively soft, the casing 12 will have maximum reciprocation while as the soil 55 compacts the reciprocation of the casing 12 and the compacting head becomes less and less and at maximum compaction is at a minimum.

On the other hand, should the compacting be done at a fixed spot, it is continued until the casing and head are substantially stationary with little or no reciprocation at which time the machine will have reached its maximum output capability.

Returning to the continuously travelling operation, when the compacting head 54 reaches an upgrade, as at 57, the head will be moved upwardly, forcing the piston 24 inwardly therewith. This, however, does not result in an increase in pressure nor increased resistance to upward movement of the compacting head since the tendency of the pressure to increase is relieved at the pressure relief valve 75. The relief valve maintains the pressure in line 73 and cylinder 24 at a constant set value regardless of the upward and downward excursions of the head 54 caused by upgrades and downgrades at surface 57 in FIGURE 1, the impactor casing 12 and head 54 thereby operating under a substantially constant down-pressure.

The rate and extent of the reciprocating excursions .of the impactor casing 12 and the parts mounted thereon will be a function of their mass relative to the mass of the freely reciprocating plunger 31, the degree of compactness of the soil 55, and the down-pressure exerted on the casing. Thus, the greater the compactness of soil, the greater the mass of the casing and the greater the downpressure, the less the throw or excursion of the casings reciprocation. Accordingly, since the down-pressure and mass of the casing remain substantially constant, the throw of the casing becomes an indication of the degree of compactness in the soil 55. This enables the operator to determine maximum compaction and maximum output capability for the machine by watching the casing 12 and determining when its throw becomes a minimum, at which point the casing should, in effect, stand substantially still while the interior plunger alone moves. This visual inspection of the casing permits the operator to determine the proper speed of movement of the tractor for continuous operation of the impactor, as in a trench or ditch,

or when to terminate the compacting operation when the impactor is stationary.

To terminate a compactor operation and raise the compacting head out of contact with the soil, the manual valve 63 is moved upwardly to interconnect ports 6467 and 65-66. This feeds hydraulic fluid under pressure directly from pump 62 to the port 76, moving the piston 26 inwardly and the casing 12 upwardly on its supporting links 16, 17. Hydraulic fluid exhausts from the port 74 and the line 73 through check valve 72 to port 66 and the tank 61. The pressurized fluid is prevented from reaching the motor 44 by the check valve 71.

In the embodiment of the invention illustrated in FIGURE 3, the impactor 81 comprises an outer cylindrical casing 82 having end plates 83 and 84. In the upper end plate 83 are threaded or otherwise secured headed pins 85 slidably mounted in sleeves 86 depending from a mounting plate 87. Compression springs 88 surround the pins 85 and sleeve 86 to bias the end plate 83 away from the mounting plate 87 and the heads of pins 85 into contact with the plate 87. Upstanding flanges 89 on the mounting plate 87 are pivotally connected to the ends of links 91, 92 interconnected by a pivotal link 93 and consituting the ends of a standard tractor backhoe boom 94. The mounting of the boom on the tractor and its hydraulic operator are of standard construction and have not been shown, it being understood that the backhoe boom is connected in conventional manner to the connecting rod of a operating piston.

To raise and lower the boom 94 and to apply a downpressure to the mounting plate 87, the boom operator is controlled by conventional backhoe valves 98 which are manually operated to raise and lower the boom and to provide down-pressure in the lowered and locked position of the boom with the mounting plate 87 in the dotted line position of FIGURE 3 and the springs 88 compressed to continue the down-pressure on the casing 82 as it moves downwardly independently of the boom.

A hearing housing 99 extends to one side of the casing 82 and communicates with its interior. A crank shaft 101 is supported on bearings 102 in the housing 99 and carries at its inner end a crank pin 103 received in a bearing 104 in the side of a freelyreci-procating, weighted plunger or piston 105 disposed within the casing 82. A guide pin 106 depends from the upper end plate 83 into a complementary end bore 107 in the plunger 105. A pair of guide pins 107 extend upwardly from the bottom end plate 84 into complementary cavities or end bores 108 in the bottom end wall of the plunger 105. The guide pins 106 and 107 maintain the plunger 105 out of contact with the interior wall of the casing, there being provided a space 109 between the plunger and the casing wall for the free passage of air past the plunger as it reciprocates. A hydraulic motor 111 is mounted on the outer end of the housing 99 and is connected to drive the crank shaft 101. The intake of pressurized hydraulic fluid to the motor 111 is through a pressure gauge 112 to line 113, the fluid exhausting through line 114 to the reservoir tank. An impact post 115 is rigidly secured, as

by welding, to the underface of the bottom end cap or end plate 84 and carries an impacting head, such as a compactor 116, at its bottom end, the head 116 and casing 82 being thereby rigidly interconnected. A post 117 extends upwardly from the upper end plate 83 to be received in a hole 118 through the mounting plate 87 to extend an indicating portion 119 to be visible above the mounting plate 87 when it is in the dotted line position of FIG- URE 3.

The control for the impactor embodiment of FIGURE 3 may include typical backhoe operating valves 98 plus an additional valve, manual or solenoid-operated, for connecting the pump to either the backhoe valves or to the motor 111. In operation, this auxiliary control valve first interconnects the pump and the backhoe valves and the backhoe valves are then operated to move the backhoe boom downwardly, moving the mounting plate 87 therewith. After the head 116 engages the soil or a post or the like to be driven, movement of the boom and mounting plate are continued until the mounting plate assumes the position shown in dotted lines in FIGURE 3, the springs 88 being compressed and exerting a downpressure on the impactor casing and head. The backhoe valves are then closed to lock the boom in position and the auxiliary valve is operated to connect the pump to the motor 111 which thereupon rotates to reciprocate the plunger 105 and affect the reactive reciprocation of the casing 82 and head 116. As the soil compacts, the casing and head move downwardly while the boom remains stationary, the springs 88 expanding until the heads of pins engage the mounting plate 87, at which time there will no longer be any down-pressure on the casing and compacting head and the rate and extent of reciprocation of the casing should increase but without useful effect. At this time, the auxiliary valve is again operated to cut ofl" supply of fluid to the motor 111 and re-connect the pump to the backhoe valves which are then again operated to move the boom 94 and the mounting plate 87 downwardly, the latter again assuming the dotted line position of FIGURE 3 with the springs 88 under compression. The boom is again locked in position by the backhoe valves and the auxiliary valve operated to connect the motor 111 to the pump for another compacting operation. This is continued until the machine reaches its maximum output capability with the soil under maximum compaction. This condition may be indicated in the embodiment of FIGURE 3 by two discrete indicating means, at the pressure gauge 112 or at the indicating end 119 of the post 117, as will now be explained.

After operation of the boom 94 to move the mounting plate 87 into the dotted line position of FIGURE 3, if the soil has not reached maximum compaction, the entire impactor will move away from the mounting plate 87 and because of the decrease in compression of the springs 88, both the throw and rate of reciprocation of the casing 82 will increase and a pressure drop will occur in the supply line 113 feeding the hydraulic motor 111. Such pressure drop may be read at the gauge 112 to indicate that maximum compaction has not been reached. On the other hand, when the machine has reached its maximum capability with the soil at maximum compaction, there will no longer be a decrease in pressure to the motor as the compactor is operated and this will indicate that the desired condition has been reached.

Likewise, at maximum compaction, the entire impactor Will no longer move downwardly relative to the mounting plate 87 and after the boom has moved it into the dotted line position of FIGURE 3, the indicating portion 119 of post 117 will remain visible above the mounting plate 87 to indicate to the operator that maximum compaction has been reached.

Only one of the indicators 112, 119 will ordinarily be used in an impactor embodiment, both being shown in FIGURE 3 to avoid duplicating the drawing figures.

In the embodiment of the invention shown in FIGURE 4, there is again a spring-connected, backhoe boom mounting, like parts being given like reference numerals in FIGURES 3 and 4, post 117, hole 118 and gauge 112 being omitted. This embodiment adds to the structure of FIGURE 3 a pair of limit switches, one at 121 mounted, for example, on the head of the left-hand pin 85 and the second at 122 mounted on the upper face of the end plate 83, the limit switches being thereby rigid with the casing 82. Limit switch 121 has on operating plunger 123 engaging the upper surface of the mounting plate 87 to be moved thereby from its normally closed position into an operated open position. Limit switch 122 has an operating plunger 124 engaging the under surface of the mounting plate 87 to be moved thereby from its normally open position into an operated closed position.

The electrical-hydraulic control diagram for the impactor embodiment of FIGURE 4 is shown in FIGURE 5. This includes a battery or other source of power 125 whose application to the electrical control circuit is controlled by a manual switch 126. A first relay 127 has an operating coil 128 in series with the normally open contact of limit switch 122, and a pair of normally open contacts 129, 131. A time delay relay 132 has on operating coil 133, a normally open contact 134, and a normally closed contact 135. An indicator light 136 is in series with the normally open contact 134. A solenoid operator 137 for a solenoid valve 138 is in series with the normally open contact 129. The hydraulic motor 111 is the same as in FIGURE 3 and is connected to a pump 139 when the solenoid 137 is energized. A reservoir tank is shown at 141 connected to the backhoe valve exhaust port 142 and to the exhaust side of the motor 111. The inlet port to the backhoe valves 98 is shown at 143 and is normally connected through the valve 138 to the pump 139. The backhoe valves 98 are connected in standard, conventional manner to the operator for the backhoe boom 94.

The operation of the impactor embodiment of FIG- URES 4 and 5 is as follows: The backhoe valves are first operated to move the backhoe boom 94 downwardly, thus lowering the impactor 81 so that the head 116 engages the soil or object to be driven and a down-pressure is applied thereto by moving the mounting plate 87 into the dotted line position of FIGURE 4, thereby compressing springs 88 which react against the upper end plate 83 on the casing 82. As the mounting plate 87 moves downwardly relative to the end plate 83, limit switch 121 contacts are first returned to their normally closed position and finally limit switch plunger 124 is engaged to operate the limit switch 122 to closed position. The backhoe valves are then moved to neutral to lock the boom in its downward position with down-pressure applied by the compressed springs 88.

If switch 126 is closed, closing of the contacts of limit switch 122 energizes both the operating coil 128 of relay 127 and the operating coil 133 of relay 132. Relay 127 operates immediately to close its contacts 129 and 131. Relay 132, however, is a time delay relay, preferably in both directions, and its contact 134 remains open and contact 135 closed for a predetermined time interval after energization of the operating coil 133. Closing of contact 131 forms a holding circuit for the operating coil 128 through contacts 121 and 135 so that relay 127 remains closed after the contacts of limit switch 122 open. Energization of solenoid 137 operates the valve 138 to disconnect the supply of pressurized fluid to the backhoe valves and initiate flow through the motor 111 to effect rotation thereof and. reciprocation of the weighted plunger 105. This causes the casing 82 to reciprocate by reactive force, as previously described. The valve 138 in blocking flow to the backhoe valves insures that the backhoe boom will be hydraulically locked in downward position, even through a backhoe valve may be actuated.

As the impactor 81 moves bodily away from the mounting plate 87, the limit switch 121 moves downwardly with the casing 82 until the plunger 123 engages the mounting plate to operate the switch 121 to open position. This deenergizes operating coils 128 and 133, thereby causing relay 127 to return to its normal position shown in FIG- URE 5 and at the same time taking the operating bias off relay 132 and terminating its timing period, the relay 132 thereby remaining in its non-operated position of FIGURE 5. The solenoid valve 137 is de-energized by the opening of contact 129 and the valve 138 returns to the position shown in FIGURE 5, disconnecting the motor 111 and connecting the backhoe valves 98 to the pump 139. At this time, the soil will not have reached maximum compaction and with the backhoe valves 98 remaining operated, the backhoe boom automatically moves downwardly to move the mounting plate 87 into the dotted line position of FIGURE 4, thereby compressing the springs 88 to apply down-pressure to the impactor. When limit switch 122 contacts close, the operation given above repeats until the soil consolidates to prevent further downward movement of the impactor 81, thereby preventing opening of the contacts of limit switch 121. The relay 132 then times out and operates to close contact 134 and light indicator light 136 and to open contact thereby deenergizing both operating coil 128 of relay 127 and operating coil 133 of relay 132. Opening of contact 129 now de-energizes solenoid 137 and terminates compacting operation and the backhoe valves may be operated to raise the impactor.

Relay 132 has been shown with a time delay in both directions so that indicator light 136 will remain on while the relay times out in returning to its normal position. If it is desired that the light 136 remain on indefinitely until switch 126 is opened, the relay 132 may be provided with a holding circuit for coil 133 or may be locked in operated position. It will be noted that the control of FIGURE 5 automatically governs the down-pressure that can be applied by the backhoe boom to the impactor since if the backhoe valves are left actuated, operation of limit switch 122 will automatically stop and lock the backhoe boom by operating the valve 38. Also, the compacting opperation is stopped at minimum down-pressure by the operation of limit switch 121 by the mounting plate 87.

The resilient attaching means provided by the springs 88 between the mounting plate 87 and the end plate 83, together with the locking of the backhoe boom in its down-pressure appyling position serves to substantially isolate the boom from the impactor, thereby substantially lessening transmission of objectionable vibrations from the impactor to the boom and the vehicle on which it is mounted. In the construction of FIGURE 1, the objectionable vibrations are somewhat similarly lessened by the cushioning effect of the hydraulic fluid in the pressure cylinder 24 cooperating with the pressure relief valve 75.

The embodiment shown in FIGURE 6 isolates the boom from the impactor and tends to eliminate objectionable vibrations by providing a compressed air cushion between the boom attachment point and the impactor. This is shown in connection with the impactor 11 of FIGURE 1 but with the mounting flanges 15 removed and the impactor mounted on the backhoe boom 94 of FIGURE 3. The ends of the backhoe beam links 91, 92 are pivotally connected to a plate rigidly mounted on a hollow piston 146. The piston 146 is reciprocable within a cylinder 147 rigidly secured and sealed to end plate 13 to provide an air chamber 148 between the end plate and the face of piston 146. The top of the cylinder 147 has an ment of the piston 146. The interior 151 of the piston 146 is connected to atmosphere through openings 152 and to the air pressure chamber 148 through a check valve 153 which insures a full supply of air at atmospheric pressure to the chamber 148 when the piston 146 is in its outermost position, thereby replenishing any air lost due to leakage from within the cylinder. An indicating finger 154 is rigidly mounted on the plate 145 and moves to the dotted line position when the backhoe 94 is supplying maximum down-pressure and with the air in chamber 148 compressed.

The operation of the FIGURE 6 embodiment is substantially the same as the FIGURE 3 embodiment, the compressed air in chamber 148 constituting a resilient connection supplying-down pressure similarly to the compressed springs 88. Measurement of the movement of case 12 by the finger 154 as the soil compact is much as described for the post 117 of FIGURE 3. As the soil consolidates beneath the impacting head, the impactor moves bodily away from the backhoe boom which is locked in position as in the operation of the FIGURE 3 embodiment. The cylinder 147 moves with the impactor and its spacing from the finger 154 increases to show that the soil is'still being compacted and the'impactormoving downwardly. As such a point in the operation that the operation that the soil reaches maximum compactiom'the impactor no longer moves away. from the reference pin 154 and their relatively stationary relation indicates that the maximum capability for the machine has been reached.

It will be understood that weighted plunger 31 and its mounting, guiding and operating elements may be utilized in the embodiments of FIGURES 3 and 4. Likewise, the weighted plunger 105 and itsmounting, guiding and operating means may be used in the embodiments of FIGURES 1 and 6. The automatic operation of FIG- URES 4 and 5 may be incorporated into the embodiments of FIGURES 3 and 6 by adding the limit switches 121 and 122 thereto in proper locations. For the hydraulic motors 4-4 and 111 there may be substituted a conventional power take-off from the engine of tractor 30.

While certain preferred embodiments of the invention have been specifically illustrated and described, it will be understood that the invention is not limited thereto as many variations will be apparent to those skilled in the art.

We claim:

1. An impacting machine comprising:

a ground support;

an impactor body portion; 7

an impactor head mounted on said body portion;

means mounting said impactor body portion on said ground support for at least vertical movement of said body portion and head relative to: the support;

means for moving said body portion and head vertically and to apply an at least initial down-pressure thereto against a surface to be impacted, in addition to the gravitational force thereon;

a weighted plunger mounted on said body portion for free reciprocating movement relative thereto without impact;

means for reciprocating said plunger to apply dynamic reaction forces to said body portion to effect reciprocation of the body portion and impacting by said head;

a crankshaft journaled in said body portion;

means interconnecting said crankshaft and said plunger for reciprocating said plunger upon rotation of said crankshaft;

motor means for eflecting rotation of said crankshaft;

said crankshaft being journaled in hearings in diametrically opposite sides of said casing above's'aid plunger; and

said connecting rod extending through a substantially vertical hole in said plunger to a wristpin extending transversely thereof.

2. An impacting machine comprising:

a ground support;

an impactor body portion;

an impactor head mounted on said body portion;

means mounting said impactor body portion on said ground support for at least vertical movement of said body portion and head relative to the support;

means for moving said body portion and head vertically and to apply an at least initial down-pressure thereto against a surface to be impacted, in addition to the gravitational force thereon;

a weighted plunger mounted on said body portion for free reciprocating movement relative thereto without impact;

means for reciprocating said plunger to apply dynamic reaction forces to said body portion to eflect reciprocation of the body portion and impacting by said head;

said means for moving and applying a down-pressure to the body portion being a hydraulic-fluid-operated piston-cylinder operator interconnecting said ground support and said body portion;

a source of pressurized hydraulic fluid;

means for controllably connecting said hydraulic fluid to said operator to exert a continuous down-pressure on said body portion;

and a pressure relief valve connected in the hydraulic system to relieve overpressures in the system otherwise caused by upward movement of the impactor head and body portion while down-pressure is being applied.

3. The impacting machine defined in claim 2 includa flow limiting regulator between said pressurized fluid source and said operator;

a hydraulic motor for reciprocating said plunger;

and means feeding said motor from said fluid source ahead of said flow limiting regulator.

4. An impacting machine comprising:

a ground support;

an impactor body portion;

an impactor head mounted on said body portion;

means mounting said impactor body portion on said ground support for at least vertical movement of said body portion and head relative to the support;

means for moving said body portion and head vertically and to apply an at least initial down-pressure thereto against a surface to be impacted, in addition to the gravitational force thereon;

a weighted plunger mounted on said body portion for free reciprocating movement relative thereto without impact;

means for reciprocating said plunger to apply dynamic reaction forces to said body portion to eflect reciprocation of the body portion and impacting by said head;

said means for moving and applying a down-pressure to the body portion being a hydraulic-fluid-operated piston-cylinder operator interconnecting said ground support and said body portion;

said mounting means including a resilient connection therein;

a source of pressurized hydraulic fluid;

means for controllably supplying said hydraulic fluid to the operator to eflect initial down-pressure on said body portion by compressing said resilient connection;

means for locking said means for moving and applying an initial down-pressure in fixed position after compression of said resilient connection whereafter downpressure on said body portion is maintained by expansion of said resilient connection as the body portion and head move bodily downward independently of the locked means;

a pair of vertically displaced limit switches;

means mounting said limit switches to be operated respectively at the maximum compression and maximum expanded conditions of said resilient connection;

electrical circuit means controlled by said limit switches for initiating operation of said plunger reciprocating means when the resilient connection is compressed and for terminating such reciprocation when the resilient connection is expanded;

and time delay means in said electrical circuit means for terminating said plunger reciprocation and giving an indication of maximum machine capability when said resilient connection does not fully expand at a predetermined time interval after initiation of plunger reciprocation.

5. An impacting machine comprising:

a ground support;

an impactor body portion;

an impactor head mounted on said body portion;

means mounting said impactor body portion on said ground support for at least vertical movement of said body portion and head relative to the support;

means for moving said body portion and head vertically and to apply an at least initial down-pressure thereto against a surface to be impacted, in addition to the gravitational force thereon;

a weighted plunger mounted on said body portion for free reciprocating movement relative thereto without impact;

means for reciprocating said plunger to apply dynamic reaction forces to said body portion to effect reciprocation of the body portion and impacting by said head;

said means for moving and applying a down-pressure to the body portion being a hydraulic-fluid-operated piston-cylinder operator interconnecting said ground support and said body portion;

said mounting means including a resilient connection therein;

a source of pressurized hydraulic fluid;

means for controllably supplying said hydraulic fluid to the operator to effect initial down-pressure on said body portion by compressing said resilient connection;

means for locking said means for moving and applying an initial down-pressure in fixed position after compression of said resilient connection whereafter downpressure on said body portion is maintained by expansion of said resilient connection as the body portion and head move bodily downward independently of the locked means;

said resilient connection including a compressed air piston-cylinder combination in which the air is compressed in the initial down pressure application and expands to maintain down-pressure on the head as the body portion and head move bodily downward.

6. An impacting machine comprising:

a ground support;

an impactor body portion;

an impactor head mounted on said body portion;

means mounting said impactor body portion on said ground support for at least vertical movement of said body portion and head relative to the support;

means for moving said body portion and head vertically and to apply an at least initial down-pressure thereto against a surface to be im-pacted, in addition to the gravitational force thereon;

a weighted plunger mounted on said body portion for free reciprocating movement relative thereto without impact;

means for reciprocating said plunger to apply dynamic reaction forces to said body portion to effect reciprocation of the body portion and impacting by said head;

said means for moving and applying a down-pressure to the body portion being a hydraulic-fluid-operated piston-cylinder operator interconnecting said ground support and said body portion;

said mounting means including a resilient connection therein;

a source of pressurized hydraulic fluid;

means for controllably supplying said hydraulic fluid to the operator to eflect initial down-pressure on said body portion by compressing said resilient connection;

means for locking said means for moving and applying an initial down-pressure in fixed position after compression of said body portion is maintained by expansion of said resilient connection as the body portion and head move bodily downward independently of the locked means;

a pair of vertically displaced limit switches:

means mounting said limit switches to be operated respectively at the maximum compression and maximum expanded conditions of said resilient connection; and

electrical circuit means controlled by said limit switches for initiating operation of said plunger reciprocating means when the resilient connection is compressed and for terminating such reciprocation when the resilient connection is expanded.

References Cited UNITED STATES PATENTS 644,014 2/1900 Jackson 173-118 968,437 8/ 1910 Wellman. 2,723,608 11/1955 Jackson a- 94-48 2,938,438 5/1960 Hamilton 94-48 3,181,442 5/ 1965 Brigel 94-48 3,253,522 5/1966 Piper 94-48 3,308,728 3/ 1967 Brown 94-48 3,376,799 4/1968 Perry et al. 94-49 ERNEST R. PURSER, Primary Examiner US. Cl. X.R. 

